Electronic systems and power supply method

An electronic system comprising an electronic device (1) having a battery cell (2) of the fuel cell can generate electric power by a chemical reaction for connection to an external device connector (34). Cell (2) may be connected by a connector (34) to the electronic device (1), and is configured by a connector (34) receiving power from the first pin of the electronic device (1), in order to activate the battery driving the auxiliary devices of the fuel cell unit (2), and configured to supply electric power generated by the fuel cell connection (34) to a second pin of the electronic device (1).